管式膜液固两相流清洗系统的研究

【作者】 郝旺春；

【导师】 杜启云； 刘恩华；

【作者基本信息】 天津工业大学 ， 材料学， 2004， 硕士

【摘要】 膜分离技术中的浓差极化和膜污染在某些方面限制了膜的应用和发展。本课题的目的在于用海绵橡胶球对污染的管式膜进行清洗，以解决一些传统的清洗方法所不能解决的问题。 首先，以硅橡胶为主要原料合成生产了海绵橡胶球；另外，以聚偏氟乙烯(PVDF)为主要原料用管式膜一体化技术生产了管式膜，并通过自行设计的检漏装置对管式膜进行检测。接着，研制了固液两相清洗系统，其中射流器、分球漏斗、管式膜支架是比较关键的几个部分。 其次，在膜领域首次提出了固液两相流体的“混流”研究方法。利用“混流”模型，建立了两相流体的剪应力模型、固体颗粒与垢层的碰撞模型和固体颗粒的运动速度模型；通过计算和理论分析，系统地考察了操作参数、颗粒物性、颗粒体积分率等对固液两相流剪应力、颗粒对垢层的碰撞力、颗粒与垢层的最大接触时间和最大接触面积的影响。 第三，通过分别测量原始样品、污染样品和海绵橡胶球清洗样品的水通量和截留率，发现三种类型的样品的通量和截留率趋势相同。而且，具体的讨论了海绵橡胶球在不同压力、海绵橡胶球数目、直径和料液的浓度等条件下对水通量的影响。为了进一步研究固液两相清洗系统，与传统的大量水冲洗法进行了比较，发现前者的恢复率较后者高出10个百分点左右。并且通过测定各个样品对卵清蛋白的截留率表明海绵橡胶球清洗并没有造成管式膜的破损。 第四，采用X射线光电子能谱(XPS)技术分析了可溶性淀粉在聚偏氟乙烯膜表面的吸附，并将XPS技术与电子显微镜技术相结合，对原始样品、污染样品和海绵橡胶球清洗样品进行了测试和分析。通过对C元素和O元素的XPS谱线解叠分析，结果表明，可溶性淀粉在聚偏氟乙烯膜面的吸附量较大，以物理沉积为主。经过海绵橡胶球清洗后效果明显增强。更多还原

【Abstract】 Concentration polarization and membrane fouling in membrane process severally limit its application and development. The paper is aimed to clean the fouled tubular membrane with rubber sponge balls in order to solve the problem which is not able to do with some traditional cleaning methods.First, rubber sponge balls are mainly synthesized with silicone rubber. In addition, tubular membrane is dominatingly made of polyvinylidene fluoride(PVDF) with the integrated production technology and the membrane is tested with self-made leak hunting device. In succession, we manufacture the solid-liquid two phase cleaning system, in which the shooting liquid device, phase break device and tubular membrane bracket are the key factors.Second, "mixed flow" is proposed for the first time as a method in membrane field. Three models are proposed as follows by applying the model of "mixed flow" : the stress of increasing fluid on fouling, collision between solid particles and fouling, and solid particles movement velocity; the effects of operating parameters, properties of particles, and the volume fraction of particles on stress in solid-liquid two phase flow, collision stress between solid particles and fouling, maximal contacting area between solid particles and fouling and maximal contacting time between solid particles and fouling are investigated systematically by calculating and theoretical analysis.Third, according to the water flux and the rejection ratio of original sample, the fouled sample and the washed sample with rubber sponge balls, we know that the same change current of the three samples. Moreover, some effect factors to water flux are discussed as follow: the operation pressure, the number and diameter of rubber sponge ball, the soluble-starch concentration, and so on. In order to study solid-liquid two phase washing system further,we compare that method with traditional mass water washing method and get the over 10% recovery ratio of the former than the latter. In addition, we test the rejection ratio of very sample and get the result of the rubber sponge ball no damnification to the membrane.Fourth, the advanced surface analysis technique -X ray photoelectron spectrum is employed to study the adsorption of soluble-starch on the PVDF membrane. Then we test by using XPS combined with SEM the original sample, the fouled sample and the washed sample with rubber sponge balls. According to the analysis of the fitting spectrum of carbon and oxygen, the result indicates that soluble-starch is adsorbed much on the membrane, but it physically deposits on the membrane. Also, the washing effect of rubber sponge balls is better.更多还原